Like what I'm sure are thousands of my fellow nineties kids, I grew up watching Grease more often than was probably healthy — and the first time I watched Danny Zuko stick out his hand to Cha Cha DiGregorio (even though I obviously hate Cha Cha DiGregorio) as the opening notes of the song "Blue Moon" began to play, I felt instinctively that a blue moon must be the most romantic thing in the world. Scratch that — the most romantic thing in the universe! So imagine my surprise (and, admittedly, disappointment) when I discovered that a blue moon is really just an astronomical phenomenon that happens on a frustratingly rare basis. I am, however, very intrigued by the fact that there are actually two of them happening this year, and I'm sure you're just as curious as I am about when we'll see the next blue moon in 2018.
For those of you who are new to this whole astronomy thing (considering the fact that my primary association with a blue moon came from a movie musical, I think it's obvious that I was a newbie until recently too), a blue moon is what we call the second of two full moons occurring in the same calendar month, per EarthSky. In order for a full moon to fit the bill, it must constitute the 13th full moon of a given year. Typically, there are 12 full moons each year, with one rising on a monthly basis.
Even a single blue moon is pretty rare — you've probably heard the phrase "once in a blue moon" used to indicate that the odds of something happening are low — so the fact that we're about experience two in a single year is actually kind of a big deal. The first blue moon of 2018 will rise on Jan. 31 (there was another blue moon on the first of the month), and it will be followed-up two months later in March. Once again, we'll see a full moon on both the first and last day of the month, which means that the Mar. 31 full moon will qualify as blue, even if it doesn't appear that way. According to Time and Date, a moon that actually looks blue in color is very rare. A blue-hued moon is usually just the result of wide dust or smoke particles in the sky.
The last time we experienced two blue moons in one year was 1999 and the next time we'll observe the same will be almost two decades from now, per EarthSky. In 2037, we'll again see two full moons in both January and March. This pattern makes sense when you consider the fact that February is a much shorter month than all the rest. February is actually the only month during which it's possible for there to be no full moon at all, which is why the bookend months of January and March both lend themselves to a blue moon. There are generally 13 full moons in a single calendar year, according to EarthSky, so if February is skipped, it's easy for the cosmos to make up the difference in the month before or after.
While the March blue moon is especially interesting since it will be the second of 2018, it will be slightly less complicated in other ways than the one we'll see on Jan. 31. The January 2018 blue moon also coincides with a lunar eclipse, which will make it appear red, aka a blood moon. Eclipses and full moons can both wreak havoc on our life here on Earth, so from an astrology perspective, that combination is really the perfect storm.